Tetrakisazo photoconductive composition and electrophotographic photoreceptor using the same

ABSTRACT

Disclosed are a photoconductive composition containing a new tetrakisazo compound of the following formula (1) and an electrophotographic photoreceptor having a photosensitive layer which contains the tetrakisazo compound of the formula (1):    &lt;IMAGE&gt;  (1) wherein R11, R12, A, Ar1, Ar2, Ar3, Ar4, Ar5, and Ar6 are defined hereinbefore. The electrophotographic photoreceptor has both high sensitivity and high durability, and the sensitivity thereof is barely lowered even after repeated use.

FIELD OF THE INVENTION

The present invention relates to a photoconductive compositioncontaining a new tetrakisazo compound and to an electrophotographicphotoreceptor having an electrophotographic light-sensitive layer whichcontains the tetrakisazo compound.

BACKGROUND OF THE INVENTION

The light-conducting process in an electrophotographic photoreceptorcomprises:

(1) a step of generating an electric charge by exposure, and

(2) a step of transporting the electric charge.

As an example of conducting both of the steps (1) and (2) in onesubstance, there is a selenium photosensitive plate. On the other hand,as an example of conducting the steps (1) and (2) separately indifferent substances, a combination comprising amorphous selenium andpoly-N-vinylcarbaxole has been well known. The method of conducting thesteps (1) and (2) separately in different substances is advantageous inthat this may broaden the range of materials available for use inelectrophotographic photoreceptors along with improving theelectrophotographic characteristics, such as sensitivity and acceptablepotential, of electrophotographic photoreceptors and, additionally,substances preferable for formation of coating films on photoreceptorsmay be selected from a broad range.

As already described by Carson in U.S. Pat. No. 2,297,691, aphotoconductive material is used in electrophotography, having asubstance which is insulating in the dark and whose electric resistancemay vary in accordance with the imagewise exposure imparted thereto,coated on a support. In general, the photographic material is firstprocessed to have a uniform surface charge in the dark, after darkadaptation for a while. Next, the material is imagewise exposed througha light-irradiating pattern which has the effect of reducing the surfacecharge in accordance with the relative energy contained in the variousparts of the light-irradiating pattern. The surface charge orelectrostatic latent image that remains on the surface of thephotoconductive substance layer (electrophotographic photosensitivelayer) is then converted into a visible image after the surface has beenbrought into contact with an appropriate charge-detecting and displayingsubstance, i.e., a toner.

The toner is contained in an insulating liquid or a dry carrier, and ineither case, this may be applied to the surface of theelectrophotographic photosensitive layer in accordance with the chargepattern formed. The displaying substance (toner) thus applied to theimage surface may be fixed by conventional means such as heat, pressureor solvent vapor. The electrostatic latent image may be transferred to asecond support (for example, paper or film). In the same manner, theelectrostatic latent image transferred to the second support may bedeveloped thereon. Electrophotography is one of image-forming methodswhere any desired images are formed in accordance with the processesmentioned above.

In such electrophotography, fundamental characteristics required forelectrophotographic photoreceptors include, for example, the following:(1) they can be charged to a pertinent potential in the dark, (2) theybarely lose the charge in the dark, and (3) they can rapidly release thecharge after light-irradiation.

The above-mentioned inorganic substances which have heretofore been usedin electrophotography have not only various merits but also variousdemerits, as a matter of fact. For example, selenium which is widelyused at present may sufficiently satisfy the above-mentioned conditions(1) to (3), but the manufacturing is difficult and complicated and themanufacturing cost is high. In addition, the manufacturing process hasno flexibility and the electrophotographic photoreceptor can barely beformed into a belt-shaped product. Further, as the electrophotographicphotoreceptor is sensitive to heat and mechanical shock, special care isrequired for handling the same. Thus selenium has various defects.Cadmium sulfide and zinc oxide are used as an electrophotographicphotoreceptor, after being dispersed in a resin as a binder. However,these electrophotographic photoreceptors have mechanical defects insmoothness, hardness, tensile strength and abrasion resistance, and sothese cannot be repeatedly used as they are.

Recently, electrophotographic photoreceptors having various organicsubstances have been suggested in order to overcome the defects of theinorganic substances, and some have been put to practical use. Forexample, there are an electrophotographic photoreceptor comprisingpoly-N-vinylcarbazole and 2,4,7-trinitrofluoren-9-one (U.S. Pat. No.3,484,237); an electrophotographic photoreceptor havingpoly-N-vinylcarbazole sensitized with a pyrylium salt dye(JP-B-48-25658) (the term "JP-B" as used hereinmeans an "examinedJapanese patent publication"); and an electrophotographic photoreceptorhaving as a main component an eutectic complex comprising a dye and aresin (JP-A-47-10735) (the term"JP-A" as used herein means an"unexamined published Japanese patent application"). In addition,electrophotographic photoreceptors having an azo pigment as a maincomponent have widely been studies recently and various proposals havebeen made as described in, for example, U.S. Pat. Nos. 3,898,084,4,618,672, 4,396,696, 4,356,243, 4,743,523, 4,666,810, 4,436,800,4,439,506, 4,447,513, 4,598,033, 4,568,623, 4,533,613, 4,619,881, and4,702,982.

The organic electrophotographic photoreceptors are superior to theabove-mentioned inorganic electrophotographic photoreceptors as theformer can have somewhat improved mechanical characteristics andflexibility. However, the organic electrophotographic photoreceptors aregenerally poor in light sensitivity when used many times and thereforethese are unsuitable for repeated use. Thus the above-mentioned organicsubstances cannot always sufficiently satisfy the requirements forelectrophotographic photoreceptors.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a newelectrophotographic photoreceptor having both high sensitivity and highdurability.

Another object of the present invention is to provide a newelectrophotographic photoreceptor whose light sensitivity barely lowerseven after repeated use.

Still another object of the present invention is to provide a newphotoconductive composition which may be used in variouselectrophotographic photoreceptors.

In order to attain these objects, the present invention provides aphotoconductive composition comprising a new tetrakisazo compound(tetrakisazo pigment) represented by the following formula (1) and alsoprovides an electrophotographic photoreceptor having anelectrophotographic photosensitive layer which contains the tetrakisazocompound.

(I) specifically, the present invention provides a photoconductivecomposition comprising at least one tetrakisazo compound represented bythe following formula (1): ##STR2## where R¹¹ and R¹² independentlyrepresent hydrogen atom or a substituted or unsubstituted alkyl, aryl oraralkyl group, and R¹¹ and R¹² may be the same or different; Ar¹, Ar²,Ar³, Ar⁴, Ar⁵, and Ar⁶ independently represent a substituted orunsubstituted arylene group;

A represents ##STR3## X represents a group that forms an aromatic ringor a heterocyclic ring, which is substituted or unsubstituted, bycondensation with the benzene ring in the aforesaid formula havinghydroxyl group and Y on the ring;

Y represents ##STR4##

R¹ represents an alkyl group, a phenyl group or a substituted groupthereof;

R² represents hydrogen atom, a lower alkyl group, a carbamoyl group, acarboxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, or asubstituted or unsubstituted amino group;

R³ represents an alkyl group, an aromatic group, a hetero-aromaticgroup, or a substituted group thereof;

R⁴ and R⁵ independently represent hydrogen atom, an alkyl group, anaromatic group, a hetero-aromatic group, or a substituted group thereof,provided that both R⁴ and R⁵ are not hydrogen atoms at the same time,and when Y represents ##STR5## R⁵ is not hydrogen atom; and

B represents a divalent group that forms an aromatic hydrocarbon or adivalent group that forms a hereto ring which contains one or morenitrogen atoms in the ring, and the ring is unsubstituted orsubstituted.

(II) The present invention further provides an electrophotographicphotoreceptor having a layer which contains a chargecarrier-transporting compound and a charge carrier-generating compoundor having a charge carrier-transporting compoound-containing layer and acharge carrier-generating compound-containing layer, on anelectroconductive support, wherein the charge carrier-generatingcompound is the tetrakisazo compound of the above-described formula (1).

DETAILED DESCRIPTION OF THE INVENTION

The tetrakisazo compounds represented by the above-described formula (1)are described in detail hereunder.

X represents a group that forms an aromatic ring (e.g., naphthalene,anthracene) or a heterocyclic ring (e.g., indole, carbazole,benzocarbazole, dibenzofuran) by condensation with the benzene ring inthe aforesaid formula having hydroxyl group and Y thereon.

When X represents a group that forms a substituted aromatic ring orhetero ring, substituents for the ring may be a halogen atom (e.g.,fluorine, chlorine, bromine), and a lower alkyl group, preferably alower alkyl group having from 1 to 8 carbon atoms (e.g., methyl, ethyl,propyl, butyl, isopropyl, isobutyl). The number of substituents may beone or two, and when two substituents are on the group, these may be thesame or different.

R¹ may be an alkyl group, preferably an alkyl group having from 1 to 12carbon atoms, or a phenyl group each of which is substituted orunsubstituted.

When R¹ represents an unsubstituted alkyl group, specific examples ofthe group include methyl, ethyl, propyl, butyl, pentyl, hexyl,isopropyl, isobutyl, isoamyl, isohexyl, neopentyl, and tert-butyl.

When R¹ represents a substituted alkyl group, substituents for the groupmay be hydroxyl group, an alkoxy group having from 1 to 12 carbon atoms,a cyano group, an amino group, an alkylamino group having from 1 to 12carbon atoms, a dialkylamino group having two alkyl groups each withfrom 1 to 12 carbon atoms, a halogen atom, and an aryl group having from6 to 15 carbon atoms. As examples of the substituted alkyl group, thereare a hydroxyalkyl group (e.g., hydroxymethyl, 2-hydroxyethyl,3-hydroxypropyl, 2-hydroxypropyl), an alkoxyalkyl group (e.g.,methoxymethyl, 2-methoxyethyl, 3-methoxypropyl, ethoxymethyl,2-ethoxyethyl), a cyanoalkyl group (e.g., cyanomethyl, 2-cyanoethyl), anaminoalkyl group (e.g., aminomethyl, 2-aminoethyl, 3-aminopropyl), an(alkylamino)alkyl group (e.g., (methylamino)methyl, 2-methylamino)ethyl,(ethylamino)methyl), a (dialkylamino)alkyl group (e.g.,(dimethylamino)methyl, 2-(dimethylamino)ethyl), a haloalkyl group (e.g.,fluoromethyl, chloromethyl, bromomethyl), and an aralkyl group (e.g.,benzyl, phenethyl).

When R¹ represents a substituted phenyl group, substituents for thegroup include hydroxyl group, an alkoxy group having from 1 to 12 carbonatoms, a cyano group, an amino group, an alkylamino group having form 1to 12 carbon atoms, a dialkylamino group having two alkyl groups eachwith from 1 to 12 carbon atoms, a halogen atom, an alkyl group havingfrom 1 to 6 carbon atoms, and a nitro group. As examples of thesubstituted phenyl group, there are hydroxyphenyl group, an alkoxyphenylgroup (e.g., methoxyphenyl, ethoxyphenyl), cyanophenyl group,aminophenyl group, an (alkylamino)phenyl group (e.g.,(methylamino)phenyl, (ethylamino)phenyl), a (dialkylamino)phenyl group(e.g., (dimethylamino)phenyl), a halophenyl group (e.g., fluorophenyl,chlorophenyl, bromophenyl), an alkylphenyl group (e.g., totyl,ethylphenyl, cumenyl, xylyl, mesityl), a nitrophenyl group as well asphenyl groups having two or three of the substituents (which may beeither the same or different). The position of the substituent and themutual relation of the positions of plural substituents, if any, are notrestricted inthe substituted phenyl group.

R² represents hydrogen atom, a lower alkyl group, preferably a loweralkyl group having from 1 to 6 carbon atoms, a carbamoyl group, acarboxyl group, an alkoxycarbonyl group, preferably an alkoxycarbonlygroup having an alkoxy group with from 1 to 12 carbon atoms, anaryloxycarbonyl group, preferably an aryloxycarbonyl group having anaryloxy group with from 6 to 20 carbon atoms or a substituted orunsubstituted amino group.

When R² represents a substituted amino group, specific examples of thegroup include methylamino, ethylamino, propylamino, phenylamino,tolylamino, benzylamino, phenethylamino, dimethylamino, diethylamino,and diphenylamino.

When R² represents a lower alkyl group, specific examples of the groupinclude methyl, ethyl, propyl, butyl, isopropyl, and isobutyl.

When R² represents an alkoxycarbonyl group, specific examples of thegroup include methoxycabonyl, ethoxycarbonyl, propoxycarbonyl,butoxycarbonyl, isopropoxycarbonyl, and benzyloxycarbonyl.

When R² represents an aryloxycarbonyl group, specific examples of thegroup include phenoxycarbonyl and tolyoxycarbonyl.

R³ represents an alkyl group, preferably an alkyl group having from 1 to20 carbon atoms, an aromatic group (e.g., phenyl, naphthyl), ahetero-romatic group, preferably a hetero-aromatic group having one ormore hetero atoms of oxygen, nitrogen and/or sulfur (e.g.,dibenzofuranyl, carbazolyl, benzocarbazolyl), or a substituted groupthereof.

When R³ represents a substituted or unsubstituted alkyl group, specificexamples of the group may be those for the above-mentioned substitutedor unsubstituted alkyl group for R¹.

When R³ represents a substituted aromatic group, such as a substitutedphenyl group or a substituted naphthyl group, or a heteroatom-containing substituted hetero-aromatic group such as a substituteddibenzofuranyl group or a substituted carbazolyl group, examples ofsubstituents for the groups include hydroxyl group, a cyano group, anitro group, a halogen atom (e.g., fluorine, chlorine, bromine), analkyl group having from 1 to 12 carbon atoms (e.g., methyl, ethyl,propyl, isopropyl), an alkoxy group having from 1 to 12 carbon atoms(e.g., methoxy, ethoxy, propoxy, butoxy, pentyloxy, isopropoxy,isobutoxy, isoamyloxy, tert-butoxy, neopentyloxy), an amino group, analkylamino group having from 1 to 12 carbon atoms (e.g., methylamino,ethylamino, propylamino), a dialkylamino group having from 1 to 12carbon atoms (e.g., dimethylamino, diethylamino, N-methyl-N-ethylamino),an arylamino group having from 6 to 12 carbon atoms (e.g., phenylamino,tolylamino), a diarylamino group having two aryl groups each with from 6to 15 carbon atoms (e.g., diphenylamino), a carboxyl group, an alkalimetal carboxylato group (examples of the alkali metal (cation) are Na+,K+ , and Li+), an alkali metal sulfonato group (examples of the alkalimetal (cation) are Na+, K+, and Li+), an alkylcarbonyl group (e.g.,acetyl, propionyl, benzylcarbonyl), an arylcarbonyl group having an arylgroup with from 6 to 12 carbon atoms (e.g., benzoyl, toluoyl), analkylthio group having from 1 to 12 carbon atoms (e.g., methylthio,ethylthio), and an arylthio group having from 1 to 12 carbon atoms(e.g., phenylthio, tolyllthio); and the number of substituents is from 1to 3. when plural substituents are on the group, these may be the sameor different in any desired combination, and the position of thesubstituents is not limited.

R⁴ and R⁵ independently represent hydrogen atom or the same group asdescribed above for R³, provided that both R⁴ and R⁵ are not hydrogenatoms at the same time.

When A represents ##STR6## the moiety ##STR7## may be positioned at anyposition of 3- to 8-positions on the naphthalene ring, and preferably atthe 8-position.

B represents a divalent group that forms an aromatic hydrocarbon or adivalent group that forms a hetero ring which contains one or morenitrogen atoms in the ring, and the ring is substituted orunsubstituted. When the ring is substituted, the substituents include analkyl group, a halogen atom, a nitro group, or hydroxyl group. Asexamples of the aromatic hydrocarbon formed by the divalent group, thereare o-phenylene, o-naphthylene, peri-naphthylene, 1,2-anthraquinonylent,and 9,10-phenanthrylene. As examples of the heterocyclic group havingone or more nitrogen atoms in the ring and formed by the divalent group,there are 3,4-pyrazole-diyl, 2,3-pyridiyl, 4,5-pyrimidine-diyl,6,7-indazole-diyl, 5,6-benzimidazole-diyl, and 6,7-quinoline-diyl.

R¹¹ and R¹² independently represent hydrogen atom or a substituted orunsubstituted alkyl, aryl or aralkyl group, and R¹¹ and R¹² may be thesame or different.

R¹¹ and R¹² may be, for example, an alkyl group such as methyl, ethyl,butyl, 2-ethylhexyl, dodecyl, or octadecyl, an aryl group such as phenylor naphthyl, or an aralkyl group such as benzyl or phenethyl.

When R¹¹ or R¹² is substituted, specific examples of the substituent forthe group include hydroxyl group, an alkoxy group having from 1 to 18carbon atoms, a cyano group, an alkyloamino group having from 1 to 18carbon atoms, a dialkylamino group having two alkyl groups each withfrom 1 to 18 carbon atoms, a halogen atom, an aryl group having from6 to15 carbon atoms, and an acyl group having up to 18 carbon atoms.

Ar¹, Ar², Ar³, Ar⁴, Ar⁵, and Ar⁶ independently represent a substitutedor unsubstituted arylene group.

As Ar¹, Ar², Ar³, Ar⁴, Ar⁵, and Ar⁶, there may be mentioned an arylenegroup such as phenylene, naphthalene, anthrylene, biphenylene, orterphenylene.

When Ar¹, Ar², Ar³, Ar⁴, Ar⁵, or Ar⁶ is substituted, specific examplesof the substituent for the group may include hydroxyl group, an alkoxygroup having from 1 to 18 carbon atoms, a cyano group, an alkylaminogroup having from 1 to 18 carbon atoms, a dialkylamino group having twoalkyl groups each with from 1 to 18 carbon atoms, a halogen atom, anaryl group having from 6 to 15 carbon atoms, and an acyl group having upto 18 carbon atoms.

The tetrakisazo compounds for use in the present invention will beillustrated further concretely hereinafter, but the examples of thecompounds mentioned below are not intended to restrict the scope of thepresent invention. For instance, specific examples of the tetrakisazocompounds are those represented by the following formula (1') where thesubstituents are indicated in Table 1 below (formulae 2 to 17). A₁ inthe formulae 2 to 17 is the coupler residue as indicated in Table 2 orTable 3 below.

                                      TABLE 1                                     __________________________________________________________________________     ##STR8##                                      [1']                           No. of                                                                        Formula                                                                            Ar.sup.1                                                                            Ar.sup.2                                                                            Ar.sup.3                                                                            R.sup.11                                                                             R.sup.12                                                                         Ar.sup.4                                                                            Ar.sup.5                                                                            Ar.sup.6                         __________________________________________________________________________    [2]                                                                                 ##STR9##                                                                            ##STR10##                                                                           ##STR11##                                                                          H      H                                                                                 ##STR12##                                                                           ##STR13##                                                                           ##STR14##                       [3]  "     "     "     CH.sub.3                                                                             "  "     "     "                                [4]  "     "     "     C.sub.2 H.sub.5                                                                      "  "     "     "                                [5]  "     "     "     n-C.sub.5 H.sub.11                                                                   "  "     "     "                                [6]  "     "     "     n-C.sub.11 H.sub.23                                                                  "  "     "     "                                [7]  "     "     "     n-C.sub.17 H.sub.35                                                                  "  "     "     "                                [8]                                                                                 ##STR15##                                                                           ##STR16##                                                                           ##STR17##                                                                          CH.sub.3                                                                             CH.sub.3                                                                          ##STR18##                                                                           ##STR19##                                                                           ##STR20##                       [9]  "     "     "     (CH.sub.2).sub.5                                                                        "     "     "                                [10] "     "     "                                                                                    ##STR21##                                                                           H  "     "     "                                [11] "     "     "                                                                                    ##STR22##                                                                           H  "     "     "                                [12] "     "     "                                                                                    ##STR23##                                                                           H  "     "     "                                [13] "     "     "                                                                                    ##STR24##                                                                           H  "     "     "                                [14]                                                                                ##STR25##                                                                           ##STR26##                                                                           ##STR27##                                                                          H      H                                                                                 ##STR28##                                                                           ##STR29##                                                                           ##STR30##                       [15] "     "     "     "      "                                                                                 ##STR31##                                                                          "     "                                [16] "     "                                                                                    ##STR32##                                                                          "      "                                                                                 ##STR33##                                                                          "     "                                [17] "     "     "                                                                                    ##STR34##                                                                           "  "     "     "                                __________________________________________________________________________

                  TABLE 2                                                         ______________________________________                                        No.                                                                           of A.sub.1                                                                          A.sub.1                                                                 ______________________________________                                        (A.sub.1 -1)                                                                         ##STR35##                                                              (A.sub.1 -2)                                                                         ##STR36##                                                              (A.sub.1 -3)                                                                         ##STR37##                                                              (A.sub.1 -4)                                                                         ##STR38##                                                              (A.sub.1 -5)                                                                         ##STR39##                                                              (A.sub.1 -6)                                                                         ##STR40##                                                              (A.sub.1 -7)                                                                         ##STR41##                                                              (A.sub.1 -8)                                                                         ##STR42##                                                              (A.sub.1 -9)                                                                         ##STR43##                                                              (A.sub.1 -10)                                                                        ##STR44##                                                              (A.sub.1 -11)                                                                        ##STR45##                                                              (A.sub.1 -12)                                                                        ##STR46##                                                              (A.sub.1 -13)                                                                        ##STR47##                                                              (A.sub.1 -14)                                                                        ##STR48##                                                              (A.sub.1 -15)                                                                        ##STR49##                                                              (A.sub.1 -16)                                                                        ##STR50##                                                              (A.sub.1 -17)                                                                        ##STR51##                                                              (A.sub.1 -18)                                                                        ##STR52##                                                              (A.sub.1 -19)                                                                        ##STR53##                                                              (A.sub.1 -20)                                                                        ##STR54##                                                              (A.sub.1 -21)                                                                        ##STR55##                                                              (A.sub.1 -22)                                                                        ##STR56##                                                              (A.sub.1 -23)                                                                        ##STR57##                                                              (A.sub.1 -24)                                                                        ##STR58##                                                              (A.sub.1 -25)                                                                        ##STR59##                                                              (A.sub.1 -26)                                                                        ##STR60##                                                              (A.sub.1 -27)                                                                        ##STR61##                                                              (A.sub.1 -28)                                                                        ##STR62##                                                              (A.sub.1 -29)                                                                        ##STR63##                                                              (A.sub.1 -30)                                                                        ##STR64##                                                              (A.sub.1 -31)                                                                        ##STR65##                                                              (A.sub.1 -32)                                                                        ##STR66##                                                              (A.sub.1 -33)                                                                        ##STR67##                                                              (A.sub.1 -34)                                                                        ##STR68##                                                              (A.sub.1 -35)                                                                        ##STR69##                                                              (A.sub.1 -36)                                                                        ##STR70##                                                              ______________________________________                                    

    TABLE 3      Ar           A.sub.1      ##STR71##      ##STR72##      ##STR73##      ##STR74##      ##STR75##      ##STR76##      ##STR77##      ##STR78##      ##STR79##      ##STR80##      A.sub.1 -37 A.sub.1 -38 A.sub.1 -39 A.sub.1 -40 A.sub.1 -41 A.sub.1 -42     A.sub.1 -43 A.sub.1 -44 A.sub.1 -45      ##STR81##      A.sub.1 -49 A.sub.1 -50 A.sub.1 -51 A.sub.1 -52 A.sub.1 -53 A.sub.1 -54     A.sub.1 -55 A.sub.1 -56 A.sub.1 -57      ##STR82##      A.sub.1 -61 A.sub.1 -62 A.sub.1 -63 A.sub.1 -64 A.sub.1 -65 A.sub.1 -66     A.sub.1 -67 A.sub.1 -68 A.sub.1 -69      ##STR83##      A.sub.1 -73 A.sub.1 -74 A.sub.1 -75 A.sub.1 -76 A.sub.1 -77 A.sub.1 -78     A.sub.1 -79 A.sub.1 -80 A.sub.1 -81      ##STR84##      A.sub.1 -85 A.sub.1 -86 A.sub.1 -87 A.sub.1 -88 A.sub.1 -89 A.sub.1 -90     A.sub.1 -91 A.sub.1      -92 A.sub.2 -93                                         Ar     A.sub.1      ##STR85##      ##STR86##      ##STR87##      ##STR88##      ##STR89##      ##STR90##      ##STR91##      ##STR92##      ##STR93##      A.sub.1 -46 A.sub.1 -47 A.sub.1 -48 A.sub.1 -97 A.sub.1 -98 A.sub.1 -99     A.sub.1 -100 A.sub.1 -101      ##STR94##      A.sub.1 -58 A.sub.1 -59 A.sub.1 -60 A.sub.1 -109 A.sub.1 -110 A.sub.1     -111 A.sub.1 -112 A.sub.1 -113      ##STR95##      A.sub.1 -70 A.sub.1 -71 A.sub.1 -72 A.sub.1 -121 A.sub.1 -122 A.sub.1     -123 A.sub.1 -124 A.sub.1 -125      ##STR96##      A.sub.1 -82 A.sub.1 -83 A.sub.1 -84 A.sub.1 -133 A.sub.1 -134 A.sub.1     -135 A.sub.1 -136 A.sub.1 -137      ##STR97##      A.sub.1 -94 A.sub.1 -95 A.sub.1 -96 A.sub.1 -145 A.sub.1 -146 A.sub.1     -147 A.sub.1 -148 A.sub.1      -149                                             Ar          A.sub.1      ##STR98##      ##STR99##      ##STR100##      ##STR101##      ##STR102##      ##STR103##      ##STR104##      ##STR105##      A.sub.1 -102 A.sub.1 -103 A.sub.1 -104 A.sub.1 -105 A.sub.1 -106     A.sub.1 -107 A.sub.1 -108      ##STR106##      A.sub.1 -114 A.sub.1 -115 A.sub.1 -116 A.sub.1 -117 A.sub.1 -118     A.sub.1 -119 A.sub.1 -120      ##STR107##      A.sub.1 -126 A.sub.1 -127 A.sub.1 -128 A.sub.1 -129 A.sub.1 -130     A.sub.1 -131 A.sub.1 -132      ##STR108##      A.sub.1 -138 A.sub.1 -139 A.sub.1 -140 A.sub.1 -141 A.sub.1 -142     A.sub.1 -143 A.sub.1 -144      ##STR109##      A.sub.1 -150 A.sub.1 -151 A.sub.1 -152 A.sub.1 -153 A.sub.1 -154     A.sub.1 -155 A.sub.1      -156

                  TABLE 4                                                         ______________________________________                                        No. of A                                                                              A.sub.1                                                               ______________________________________                                        (A.sub.1 -157)                                                                         ##STR110##                                                           (A.sub.1 -158)                                                                         ##STR111##                                                           (A.sub.1 -159)                                                                         ##STR112##                                                           (A.sub.1 -160)                                                                         ##STR113##                                                           (A.sub.1 -161)                                                                         ##STR114##                                                           (A.sub.1 -162)                                                                         ##STR115##                                                           (A.sub.1 -163)                                                                         ##STR116##                                                           (A.sub.1 -164)                                                                         ##STR117##                                                           (A.sub.1 -165)                                                                         ##STR118##                                                           (A.sub.1 -166)                                                                         ##STR119##                                                           (A.sub.1 -167)                                                                         ##STR120##                                                           (A.sub.1 -168)                                                                         ##STR121##                                                           (A.sub.1 -169)                                                                         ##STR122##                                                           (A.sub.1 -170)                                                                         ##STR123##                                                           (A.sub.1 -171)                                                                         ##STR124##                                                           (A.sub.1 -172)                                                                         ##STR125##                                                           (A.sub.1 -173)                                                                         ##STR126##                                                           (A.sub.1 -174)                                                                         ##STR127##                                                           (A.sub.1 -175)                                                                         ##STR128##                                                           (A.sub.1 -176)                                                                         ##STR129##                                                           (A.sub.1 -177)                                                                         ##STR130##                                                           (A.sub.1 -178)                                                                         ##STR131##                                                           (A.sub.1 -179)                                                                         ##STR132##                                                           (A.sub.1 -180)                                                                         ##STR133##                                                           (A.sub.1 -181)                                                                         ##STR134##                                                           (A.sub.1 -182)                                                                         ##STR135##                                                           (A.sub.1 -183)                                                                         ##STR136##                                                           (A.sub.1 -184)                                                                         ##STR137##                                                           ______________________________________                                    

The new tetrakisazo compounds for use in the present invention can beproduced with ease by conventional methods. For example, the tetrakisazocompounds of the aforesaid formula (2) can be produced by the methoddescribed below.

The compound of the following formula (18) whee R is hydrogen atom,which may be obtained with ease by tetraphenylating4,4"-diaminodiphenylmethane (a product of Aldrich Chemical Co.), isnitrated with nitric acid under appropriate conditions, for example, inacetic anhydride to obtain a compound of the formula (18) where R is anitro group. Next, the resulting compound is reduced under appropriateconditions, for example, with iron powder and dilute hydrochloric acidor with stannous chloride and hydrochloric acid, to give a compound ofthe formula (18) where R is NH₂. Next, the compound is diazotized andthen coupled with the corresponding coupler (e.g., naphthol AS) wherebythe intended tetrakisazo compound of the formula (18) can be obtainedwith ease. As one specific example, production of the compound of theformula (2) where A₁ is No. A₁ -21 is illustrated hereunder. ##STR138##

13.7 g (0.02 mol) of 4,4"-bis(N,N-bis-p-nitrophenylamino)diphenylmethane(compound (1)) was blended with 400 ml of N,N-dimethylformamide and 22 gof iron powder, and 11 ml of concentrated hydrochloric acid and 32 ml ofwater were added to the resulting mixture and heated to 100° C. whilestirring well. After reacting for 3 hours, the reaction mixture wasneutralized with an aquenous saturated sodium carbonate solution to Ph=8while keeping at 100° C., and then filtered while hot. The resultingfiltrate was poured into 2 liter of ice-water, and the amino compound(2) precipitated was taken out by filtration and dried. Yield: 6.75 g(60%).

Next, 5.63 g (0.01 mol) of the amino compound (2) was added to dilutehydrochloric acid prepared from 25 of concentrated hydrochloric acid and30 ml of water and stirred well on a water bath (60° C.) for about 30minutes. Then the resulting mixture was cooled to 0° C. and a solutionof 3.04 g of sodium nitrite dissolved in 10 ml of water was addeddropwise thereto at 0° C. over a period of about 20 minutes. Afterwards,the entire mixture was stirred at the same temperature for one hour, anda small amount of unreacted substances was filtered off. The resultingfiltrate was added dropwise to a mixture comprising 15.3 g (0.04 mol) ofthe coupler (A₁ -21)-H and 100 ml of pyridine, which had been preparedin a different container, with ice-cooling and stirring. Afterwards, theentire mixture was stirred for 2 hours at room temperature and thereaction was finished. The reaction mixture was poured into 500 ml ofwater, and the crystals precipitated were removed by filtration. Thethus obtained crude crystals were repeatedly washed with acetone. Thus11.3 g of the compound (3) was obtained in the form of a black powder.Yield: 53% relative to the amino compound (2).

Decomposition Temperature: 250° C. or higher.

Elemental Analysis (C₁₃₃ H₉₄ O₁₂ N₁₈):

Calculated C 74.78%, H 4.44%, N 11.80%

Measured C 74.56%, H 4.34%, N 11.73%

IR Absorption Spectrum (KBr tablet method):

νNH: 3250 to 3450 cm⁻¹

νV=O: 1660 cm⁻¹

The electrophotographic photoreceptor of the present invention has anelectrophotographic photosensitive layer which contains one or more ofthe tetrakisazo compounds of the aforesaid formula. Electrophotographicphotoreceptors of various types have been known, and any known type mayapply to the electrophotographic photoreceptor of the present invention.Preferably, the photoreceptor of the invention has one of the followingtypes of structures.

(I) An electrophotographic photosensitive layer having the particulartetrakisazo compound dispersed in a binder or a chargecarrier-transporting medium is provided on an electroconductive support.

(II) A charge carrier-generating layer composed mainly of the particulartetrakisazo compound is provided on an electroconductive support and acharge carrier-transporting medium layer is superposed over the chargecarrier-generating layer.

The tetrakisazo compound of the present invention acts as aphotoconductive substance, and when this absorbs light, a charge carrierwith an extremely high efficiency is generated. The thus generatedcharge carrier may be transported via the tetrakisazo compound as atransporting medium, but it is more effective to be transported via acharge carrier-transporting compound as a transporting medium.

For formation of the electrophotographic photoreceptor of type (I), finegrains of the tetrakisazo compound of the invention are dispersed in abinder solution or in a solution containing a chargecarrier-transporting compound and a binder and the resulting dispersionmay be coated on an electroconductive support and dried. The thicknessof the electrophotographic photosensitive layer formed is preferablyfrom 3 to 30 μ, especially from 5 to 30 μ.

For formation of the electrophotographic photoreceptor of type (II), thetetrakisazo compound of the invention is coated on an electroconductivesupport by vacuum evaporation plating, or a solution of the compounddissolved in a solvent such as an amine is coated on the support, or adispersion of fine grains of the compound dispersed in an appropriatesolvent optionally containing a binder dissolved therein is coated onthe support; and, after drying the thus-coated layer, a solutioncontaining a charge carrier-transporting compound and a binder issuperposed over the layer and dried. The thickness of the tetrakisazocompound-containing layer, which is a charge carrier-generating layer,is preferably from 0.01 to 4 μ, especially 2 μ or less; and thethickness of the charge carrier-transporting medium layer is preferablyfrom 3 to 30 μ, especially from 5 to 20 μ.

The tetrakisazo compound is to be used for formation of thephotoreceptors of types (I) and (II) is in the form of fine grainshaving a grain size of 5 μ or less, preferably 2 μ or less, as milled ina ball mill, a sand mill, a vibration mill or the like dispersingmachine.

In the formation of the electrophotographic photoreceptor of type (I),if the amount of the tetrakisazo compound used is too small, thesensitivity is poor, but if too large, the charging property is poor andthe strength of the photosensitive layer formed is low. Accordingly, theproportion of the tetrakisazo compound in the electrophotographicphotosensitive layer is preferably from 0.01 to 2 times by weight,especially from 0.05 to 1 time by weight, of the binder therein. Theproportion of the charge carrier-transporting compound, if any, ispreferably from 0.1 to 2 times by weight, especially from 0.3 to 1.3times by weight, of the binder therein. If the chargecarrier-transporting compound used acts also as a binder, the amount ofthe tetrakisazo compound to be added is preferably from 0.01 to 0.5 timeby weight of the binder.

In formation of the tetrakisazo compound-containing layer, which is acharge carrier-generating layer, for producing the electrophotographicphotoreceptor of type (II), the amount of the tetrakisazo compound ispreferably from 0.1 to 20 times by weight of the binder. If less thanthis, the resulting layer does not have sufficient light sensitivity.The proportion of the charge carrier-transporting compound in the chargecarrier-transporting medium is preferably from 0.2 to 2 times by weight,especially from 0.3 to 1.3 times by weight, of the binder in the medium.If a charge carrier-transporting high-molecular weight compound whichacts also as a binder is used, any other binder is unnecessary.

In the formation of the electrophotographic photoreceptor of the presentinvention, additives, such as plasticizers or sensitizing agents may beused together with the binder.

The electroconductive support for use in the electrophotographicphotoreceptor of the present invention may be a metal plate such as analuminium, copper or zinc plate, a plastic sheet or film (e.g., apolyester sheet or film) coated with an electroconductive material(e.g., iridium oxide, SnO₂) by vacuum evaporation plating or dispersioncoating, or a paper processed to have electroconductivity.

As a binder, it is preferred to use an electrically insulating andfilm-forming high-molecular weight polymer which is hydrophobic andwhich has a high dielectric constant. Examples of suitablehigh-molecular weight polymers are set forth below, which, of course,are not limitative.

Polycarbonate, polyester, methacrylic resin, acrylic resin, polyvinylchloride, polyvinylidene chloride, polystyrent, polyvinyl acetate,styrene/butadiene copolymer, vinylidene chloride/acrylonitrilecopolymer, vinyl chloride/vinyl acetate copolymer, vinyl chloride/vinylacetate/maleic anhydride copolymer, silicone resin, silicone-alkydresin, poly-N-vinylcarbazole.

These binders may be used singly or in the form of a mixture of two ormore.

As a plasticizer, there may be mentioned, for example, biphenyl,biphenyl chloride, o-terphenyl, p-terphenyl, dibutyl phthalate,dimethylene glycol phthalate, dioctyl phthalate, triphenyl phosphate,methylnaphthalene, benzophenone, chlorinated paraffin, polypropylene,polystyrene, dilaurylthio dipropionate, 3,5-dinitrosalicylic acid, andvarious fluorohydrocarbons.

In addition, a silicone oil or the like may be added so as to improvethe surface property of the electrophotographic photoreceptor.

As a sensitizing agent, there may be mentioned, for example, chloranyl,tetracyanoethylene, Methyl Violet, Rhodamine B, cyanine dyes,merocyanine dyes, pyrylium dyes, and thiapyrylium dyes.

Charge carrier-transporting compounds are generally grouped into twogroups, electron-transporting compounds and positive hole-transportingcompounds. Both of the groups may be used in the electrophotographicphotoreceptor of the present invention. The electron-transportingcompounds are electron-attracting group-containing compounds, whichinclude, for example, 2,4,7-trinitro-9-fluorenone,2,4,5,7-tetranitro-9-fluorenone,9-dicyanomethylene-2,4,7-trinitrofluorenone,9-dicyanomethylene-2,4,5,7-tetranitrofluorenone,tetranitrocarbazole-chloranyl,2,3-dichloro-5,6-dicyanobenzsoquinone,2,4,7-trinitor-9,10-phenanthrenequinone,tetrachlorophthalic anhydride, tetracyanoethylene, andtetracyanoquinodimethane.

The positive hole-transporting compounds are electron-donatinggroup-containing compounds, and examples of the compounds are set forthbelow.

High-Moledular Weight Compounds:

(1) Polyvinylcarbazole and derivatives thereof described inJP-B-34-10966.

(2) Vinyl polymers (e.g., polyvinylpyrene, polyvinylanthracene,poly-2-vinyl-4-(4'-dimethylaminophenyl)-5-phenyloxazole,poly-3-vinyl-N-ethylcarbazole) described in JP-B-43-18674 andJP-B-43-19192.

(3) Polymers (e.g., polyacenaphthylene, polyindene,acenaphthylene/styrene copolymer) described in JP-B-43-19193.

(4) Condensed resins (e.g., pyrene/formaldehyde resin,bromopyrene/formaldehyde resin, ethylcarbazole/formaldehyde resin)described in JP-B-56-13940.

(5) Various triphenylmethane polymers described in JP-A-56-90883 andJP-A-56-161550.

Low-Molecular Weight Compounds:

(6) Triazole derivatives described in U.S. Pat. No. 3,112,197.

(7) Oxadiazole derivatives described in U.S. Pat. No. 3,189,447.

(8) Imidazole derivatives described in JP-B-37-16096.

(9) Polyarylalkane derivatives described in U.S. Pat. Nos. 3,615,402,3,820,989 and 3,542,544, JP-B-45-555, JP-B-51-10983JP-A-51-93224,JP-A-55-108667, JP-A-55-156953, and JP-A-56-36656.

(10) Pyrazoline derivatives and pyrazolone derivatives described in U.S.Pat. Nos. 3,180,729 and 4,278,746, JP-A-55-88064, JP-A-55-88065,JP-A-49-105537, JP-A-55-51086, JP-A-56-80051, JP-A-56-88141,JP-A-57-45545, JP-A-54-112637, and JP-A-55-74546.

(11) Phenylenediamine derivatives described in U.S. Pat. No. 3,615,404,JP-B-51-10105, JP-A-54-83445, JP-A-54-110836, JP-A-54-119925,JP-B-46-3712, and JP-B-47-28336.

(12) Arylamine derivatives described in U.S. Pat. No. 3,567,450,JP-B-49-35702, West German Patent (DAS) 1,110,518, U.S. Pat. Nos.3,180,703, 3,240,597, 3,658,520, 4,232,103, 4,175,961 and 4,012,376,JP-A-55-144250, JP-A-56-119132, JP-B-3927577, and JP-A-56-22437.

(13) Amino-substituted chalcone derivatives described in U.S. Pat. No.3,526,501.

(14) N,N-bicarbazyl derivatives described in U.S. Pat. No. 3,542,546.

(15) Oxazole derivatives described in U.S. Pat. No. 3,257,203.

(16) Styrylanthracene derivatives described in JP-A-56-46234.

(17) Fluorenone derivatives described in JP-A-54-110837.

(18) Hydrazone derivatives described in U.S. Pat. No. 3,717,462,JP-A-54-59143 (corresponding to U.S. Pat. No. 4,150,987), JP-A-55-52063,JP-A-55-52064, JP-A-55-46760, JP-A-55-85495, JP-A-57-11350,JP-A-57-148749, and JP-A-57-104144.

(19) Benzidine derivatives described in U.S. Pat. Nos. 4,047,948,4,047,949, 4,265,990, 4,273,846, 4,299,897 and 4,306,008.

(20) Stilbene derivatives described in JP-A-58-190953, JP-A-59-95540,JP-A-59-97148, JP-A-59-195658, and JP-A-62-36674.

The charge carrier-transporting compounds for use in the presentinvention are not limited to only the above-mentioned compounds (1) to(20) but any other known charge carrier-transporting compounds may ofcourse be used in the present invention.

Two or more kinds of charge carrier-transporting compounds can be usedtogether, if desired.

In the photoreceptor thus obtained in accordance with the presentinvention, an adhesive layer or a barrier layer may optionally beprovided between the electroconductive support and the photosensitivelayer, if desired. As the materials to be used for formation of theoptional adhesive or barrier layer, there are the above-mentionedhigh-molecular weight polymers which may be used for a binder, as wellas gelatin, casein, polyvinyl alcohol, ethyl ceuulose, carboxymethylcellulose, the vinylidene chloride polymer latex described inJP-A-59-84247, the styrene/butadiene polymer latex described inJP-A-59-114544, and aluminium oxide. The thickness of the layer ispreferably 1 μm or less.

As described in detail above, the electrophotographic photoreceptor ofthe present invention is characterized by high sensitivity and superiordurability.

The electrophotographic photoreceptor of the present invention maywidely be applied to various fields of electrophotographic copyingmachines as well as printers using a laser beam or a Braun tube as alight source.

The tetrakisazo compound-containing photoconductive composition of thepresent invention can be used as a photoconductive layer in apicture-taking tube in a video camera, or as a photoconductive layer ina picture-taking solid element which has a light-receiving layer(photoconductive layer) provided on the entire surface of a knownone-dimensionally or two-dimensionally arranged semiconductor circuitfor transportation or scanning of signals. In addition, the compositionmay also be used as a photoconductive layer for a solar battery, asdescribed in A. K. Ghosh and Tom Feng, J. Appl. Phys., 49 (12), 5982(1978).

Further, the tetrakisazo compound of the present invention can also beused as photoconductive colored grains in a photoelectrophoresis systemor as colored grains in dry or wet electrophotographic developer.

In accordance with the disclosure in JP-B-37-17162, JP-A-55-19063,JP-A-55-161250, and JP-A-57-147656, the tetrakisazo compound of thepresent invention can be dispersed in the above-mentioned bhargecarrier-transporting compound (e.g., oxadiazole derivatives, hydrazonederivatives) together with an alkali-soluble resin liquid (e.g., phenolresin), and the resulting dispersion may be coated and dried on anelectroconductive support (e.g., aluminium). Then the thus coatedsupport is imagewise exposed, developed with a toner, and etched with anaqueous alkaline solution to obtain a printing plate having highresolving power, high durability and high sensitivity. In the samemanner, a printed circuit may also be prepared.

The following examples are intended to illustrate the present inventionin greater detail but not to limit it in any way. Unless otherwiseindicated, the term "part" means "part by weight". Also, unlessotherwise indicated, cell percents, ratios, etc. are by weight.

EXAMPLE 1

One part of the tetrakisazo compound of the formula (2) where A₁ is No.A₁ -21 (prepared in the aforesaid Production Example), 5 parts of4,4'-bis(diethylamino-2,2'-dimethyltriphenylmethane and 5 parts ofpolycarbonate of bisphenol A were added to 95 parts of dichloromethaneand milled and blended in a ball mill to prepare a coating liquid. Thiswas coated on an electroconductive transparent support (prepared bycoating indium oxide film on the surface of a 100 μm polyethyleneterephthalate film by vacuum evaporation plating, and having a surfaceresistance of 10³ Ω) with a round wire rod and dried to obtain anelectrophotographic photoreceptor having a mono-layeredelectrophotographic photoconductive layer with a thickness of about 8μm.

For testing the thus prepared electrophotographic photoreceptor, anelectrostatic copying tester (SP-428 type, manufactured by KawaguchiElectric Co.) was used. Briefly, the photoreceptor was charged to be+400 V by corona discharge of +5 kV and a light was irradiated theretowith a tungsten lamp (color temperature: 2854° K.) so that the surfacewas 4 lux. The time required for decaying the surface potential to onehalf of the initial surface potential was obtained, and the half-valueexposure E₅₀ (lux.sec) was calculated therefrom, which was 7.2 lux.sec.

EXAMPLES 2 TO 11

The process of Example 1 was repeated except that the tetrakisazocompound shown in Table 5 below was used in place of the tetrakisazocompound produced by the Production Example. Thus various mono-layeredelectrophotographic photoreceptors were prepared, and these were testedin the same manner as in Example 1. The half-value exposure E₅₀ bypositive charge was obtained in each sample. The results obtained areshown in Table 5.

                  TABLE 5                                                         ______________________________________                                                 Tetrakisazo Compound                                                 Example No.                                                                              No. of Formula                                                                              A.sub.1 E.sub.50 (lux · sec)                ______________________________________                                        2          (2)           A.sub.1 -22                                                                           3.6                                          3          (2)           A.sub.1 -1                                                                            4.5                                          4          (2)           A.sub.1 -5                                                                            13.1                                         5          (2)           A.sub.1 -53                                                                           4.0                                          6          (2)           A.sub.1 -157                                                                          5.7                                          7          (2)           A.sub.1 -167                                                                          6.1                                          8          (7)           A.sub.1 -21                                                                           3.5                                          9          (9)           A.sub.1 -21                                                                           6.0                                          10         (12)          A.sub.1 -21                                                                           2.9                                          11         (12)          A.sub.1 -22                                                                           7.5                                          ______________________________________                                    

EXAMPLE 12

5 parts of the tetrakisazo compound if the formula (2) where A₁ is No.A₁ -21 (prepared in the aforesaid Production Example) was dispersed in asolution of 5 parts of polyester resin (trade name: Vilon® 20, by ToyoboCo., Ltd.) dissolved in 50 parts of tetrahydrofuran, by ball milling for20 hours, and the resulting dispersion was coatd on an electroconductivesupport (prepared by coating an aluminium coat on the surface of a 75 μmpolyethylene terephthalate film by vacuum evaporation plating, andhaving a surface electric resistance of 4×10² Ω) with a round wire rodand dried to form a 0.5 μm thick charge-generating layer.

Next, a solution of 3.6 parts ofp-(diphenylamino)benzaldehyde-N'-methyl-N'-phenylhydrazone representedby the following formula: ##STR139## and 4 parts of polycarbonate ofbisphenol A dissolved in 13.3 parts of dichloromethane and 26.6 parts of1,2-dichloroethane was overcoated on the charge-generating layer with around wire rod and dried to form an 11 μm thick charge-transportinglayer thereon. Thus an electrophotographic photoreceptor having atwo-layered photosensitive layer was prepared.

Next, the photoreceptor was charged by corona discharge of -6 kV, andthe initial surface potential was represented by V₀. Then this wasirradiated with light from a tungsten lamp so that the illuminance onthe surface was 30 lux, and the exposure (E₅₀) necessary for decayingthe surface potential to one half of the initial surface potential V₀was measured. Also, the surface potential (residual potential V_(r))after exposure with 60 lux.sup..sec was measured.

The same measurement was also conducted after 3000 repetitions. Therequests obtained are shown in Table 6 below.

                  TABLE 6                                                         ______________________________________                                                     1st Time                                                                             3000th Time                                               ______________________________________                                        V.sub.0 (V)    -720     -710                                                  E.sub.50 (lux · sec)                                                                5.2      5.4                                                   V.sub.R (V)    -5       -6                                                    ______________________________________                                    

EXAMPLES 13 TO 22

The process of Example 12 was repeated except that the tetrakisazocompound shown in Table 7 below was used in place of the tetrakisazocompound of Example 12. Thus various two-layered electrophotographicphotoreceptors were prepared, and these were tested in the same manneras in Example 12. The half-value exposure E₅₀ was obtained in eachsample. The results are shown in Table 7.

                  TABLE 7                                                         ______________________________________                                        Example No.                                                                              No. of Formula                                                                              A.sub.1 E.sub.50 (Lux · sec)                ______________________________________                                        13         (2)           A.sub.1 -22                                                                           3.4                                          14         (2)           A.sub.1 -1                                                                            4.2                                          15         (2)           A.sub.1 -5                                                                            11.0                                         16         (2)           A.sub.1 -53                                                                           3.6                                          17         (2)           A.sub.1 -157                                                                          5.2                                          18         (2)           A.sub.1 -167                                                                          6.3                                          19         (7)           A.sub.1 -21                                                                           3.0                                          20         (9)           A.sub.1 -21                                                                           7.0                                          21         (12)          A.sub.1 -21                                                                           2.8                                          22         (12)          A.sub.1 -22                                                                           6.0                                          ______________________________________                                    

EXAMPLE 23

5 parts of the tetrakisazo compound of the formula (2) where A₁ is No.A₁ -21 (prepared in the Production Example), 40 parts of the hydrazonecompound used in Example 12, and 100 parts of a benzylmethacrylate/methacrylic acid copolymer ([η]=0.12 at 30° C. in methylethyl ketone, methacrylic acid content: 32.9%) were added to 660 partsof dishloromethane and ultrasonically dispersed.

The resulting dispersion was coated on a sand-processed 0.25 mm-thickaluminium plate and dried to prepare an electrophotographicphotosensitive printing plate material having an electrophotographicphotosensitive layer with a dry thickness of 6 μm.

The sample was charged by corona discharge (+6 kv) in the dark so thatthe surface potential of the photosensitive layer was charged to beabout +600 V. Next, a tungusten light (color temperature: 2854° K.) wasirradiated on the surface of the sample with an illuminance of 2.0 lux,whereupon the half-value exposure E₅₀ was 6.2 lux.sup..sec.

Next, the sample was charged to have a surface potential of about +400 Vin the dark and then imagewise exposed through a positive image-havingtransmittable original attached thereto. The thus exposed sample wasdipped in a liquid developer containing a toner prepared by adding 5parts of fine polymethyl methacrylate grain (toner) dispersion and 0.01part of soybean lecithin to 1000 parts of Isoper® H (petroleum solvent,manufactured by Esso Standard Co.), to obtain a sharp positive tonerimage.

Then this was heated at 100° C. for 30 seconds to fix the toner image.The thus prepared printing plate material was dipped in a solution of 70parts of sodium metasilicate hydrate dissolved in 140 parts of glycerin,550 parts of ethylene glycol and 150 parts of ethanol for about 1 minuteand then washed by gently brushing the surface with flowing water,whereby the photosensitive layer to which the toner had not been adheredwas removed. Thus a printing plate was obtained.

In place of the liquid developer, the electrostatic latent image wasdeveloped by magnetic brush-development with Xerox® 3500 Toner(manufactured by Fuji Xerox Co., Ltd.) and then heated at 80° C. for 30seconds for fixation. Then the photosensitive layer with no toner wasremoved by the use of an alkaline solution to obtain a printing plate.

The thus prepared printing plate was placed in a Hamada Star 600 CDoffset printing machine and printing was conducted in a conventionalmanner. 50,000 prints which were all extremely sharp with no backgroundstain could not obtained.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A photoconductive composition comprising at leastone tetrakisazo represented by the following formula (1): ##STR140##where R¹¹ and R¹² independently represent hydrogen atom or a substitutedor unsubstituted alkyl, aryl or aralkyl group, and R¹¹ and R¹² may bethe same or different or R¹¹ and R¹² may be taken together to form aring; Ar¹, ar², Ar³, Ar⁴, Ar⁵, and Ar⁶ independently represent asubstituted or unsubstituted arylene group;A represents ##STR141## Xrepresents a group that forms an aromatic ring or a heterocyclic ring,which is substituted or unsubstituted, by condensation with the benzenering in the aforesaid formula having a hydroxyl group and Y on the ring;Y represents ##STR142## R¹ represents an alkyl group, a phenyl group ora substituted group thereof; R² represents a hydrogen atom, a loweralkyl group, a carbamoyl group, a carboxyl group, an alkoxycarbonylgroup, an aryloxycarbonyl group, or a substituted or unsubstituted aminogroup; R³ represents an alkyl group, an aromatic group, ahetero-aromatic group, or a substituted group thereof; R⁴ and R⁵independently represent a hydrogen atom, an alkyl group, an aromaticgroup, a hetero-aromatic group, or a substituted group thereof, providedthat both R⁴ and R⁵ are not hydrogen atoms at the same time, and when Yrepresents ##STR143## R⁵ is not a hydrogen atom; and B represents adivalent group that forms an aromatic hydrocarbon or a divalent groupthat forms a hetero ring which contains one or more nitrogen atoms inthe ring, and the ring is unsubstituted or substituted.
 2. A compositionas in claim 1, wherein said aromatic group represented by R³, R⁴ and R⁵is a phenyl group or a naphthyl group; and said hetero-aromatic grouprepresented by R³, R⁴, and R⁵ is a hetero-aromatic group having one ormore hetero atoms of oxygen, nitrogen and/or sulfur.
 3. A composition asin claim 1, wherein said divalent group that forms an aromatichydrocarbon, represented by B, is an o-phenylene group, an o-naphthylenegroup, a peri-naphthylene group, a 1,2-anthraquinolene group, or a9,10-phenanthrylene group; and said divalent group that forms a heteroring, represented by B, is a 3,4-pyrazolediyl group, a 2,3-pyridiylgroup, a4,5-pyrimidine-diyl group, a 6,7-indazole-diyl group, a5,6-benzimidazole-diyl group, or a6,7-quinoline-diyl group.
 4. Acomposition as in claim 1, wherein said arylene group represented byAr¹, Ar², Ar³, Ar⁴, Ar⁵, and Ar⁶ is a phenylene group, a naphthalenegroup, an anthrylene group, a biphenylene group, or a terphenylenegroup.
 5. An electrophotographic photoreceptor having a layer whichcontains a charge carrier-transporting compound and a chargecarrier-generating compound on an electroconductive support, wherein thecharge carrier-generating compound is the tetrakisazo compound asclaimed in claim
 1. 6. An electrophotographic photoreceptor having acharge carrier-transporting compound-containing layer and a chargecarrier-generating compound-containing layer on an electroconductivesupport, whrein the charge carrier-generating compound is thetetrakisazo compound as claimed in claim
 1. 7. A photoreceptor as inclaim 5, wherein said layer further comprises a binder.
 8. Aphotoreceptor as in claim 6, wherein said charge carrier-generatingcompound-containing layer contains said tetrakisazo compound as a majorcomponent, and said charge carrier-transporting compound-containinglayer is provided on said charge carrier-generating compound-containinglayer.
 9. A photoreceptor as in claim 5, wherein said layer has athickness of from 3 to 30 μ.
 10. A photoreceptor as in claim 9, whereinsaid layer has a thickness of from 5 to 20 μ.
 11. A photoreceptor as inclaim 8, where said charge carrier-generating compound-containing layerhas a thickness of from 0.01 to 4 μ, and said chargecarrier-transporting compound-containing layer has a thickness of from 3to 30 μ.
 12. A photoreceptor as in claim 11, wherein said chargecarrier-generating compound-containing layer has a thickness of from0.01 to 4 μ, and said charge carrier-transporting compound-containinglayer has a thickness of from 5 to 20 μ.
 13. A photoreceptor as in claim5, wherein said layer further contains a binder, said tetrakisazocompound is present in said layer in an amount of from 0.01 to 2 timesthe weight of said binder, and said charge carrier-transporting compoundis present in said layer in an amount of from 0.1 to 2 times the weightof said binder.
 14. A photoreceptor as in claim 13, wherein saidtetrakisazo compound is present in said layer in an amount of from 0.05to 1 times the weight of said binder, and said chargecarrier-transporting compound is present in said layer in an amount offrom 0.3 to 1.3 times the weight of said binder.
 15. A photoreceptor asin claim 5, wherein said tetrakisazo compound is present in said layerin an amount of from 0.01 to 0.5 times the weight of said chargecarrier-transporting compound.
 16. A photoreceptor as in claim 6,wherein said charge carrier-generating compound-containing layer furthercontains a binder, the amount of said tetrakisazo compound being from0.1 to 20 times the weight of said binder, and said chargecarrier-transporting compound-containing layer further contains abinder, the compound of said charge carrier-transporting compound beingfrom 0.2 to 2 times the weight of said binder.
 17. A photoreceptor as inclaim 16, wherein the amount of said tetrakisazo compound in said chargecarrier-generating compound-containing layer is from 0.1 to 20 times theweight of said binder, and the amount of said chargecarrier-transporting compound in said charge carrier-transportingcompound-containing layer is from 0.3 to 1.3 times the weight of saidbinder.